Men are less aggressive after smelling women’s tears: study

Weird But True

By Alexandra Klausner

Read it and weep. 

Men are less aggressive after smelling women’s tears, according to study findings published Thursday in PLOS Biology.

The research, carried out by the Weizmann Institute of Science in Israel, found that human tears contain a chemical signal that reduces activity in two aggression-related brain regions.

When researchers sought volunteers for the study, mostly women raised their hands “because for them it’s much more socially acceptable to cry,” Ph.D. student Shani Agron, who spearheaded the work, said in a statement. 

However, the researchers hypothesized that the tears don’t need to come from a woman to have a similar effect.

Previous studies with rodents found that female mouse tears reduce fighting among male mice, and male mole rats smear themselves with their own tears to avoid being attacked by alpha mice, the Weizmann Institute noted.

Scientists said other research also shows that sniffing tears reduces testosterone. 

“Given previous findings showing lower testosterone levels in men following sniffing tears and the findings in rodents showing that tears reduce aggression, we hypothesized that tears would act the same in humans; however, we were surprised by the size of the effect in the lab,” Agron told Newsweek.

After collecting tears from six female volunteers who watched sad films, researchers exposed dozens of men to the tears or a saline liquid.

They couldn’t distinguish between the substances since both are clear and odorless. 

The men then played a computer game, used in other aggression studies, with players collecting money that their opponent attempts to steal from them.

Players can get revenge and make their opponent lose money, even though they wouldn’t gain more money for themselves.

After smelling women’s tears, the men’s desire to seek revenge fell 43.7%.

These results are similar to the study findings involving rodents, but unlike rodents, humans don’t have a structure in their noses that detects odorless chemical signals.  

The researchers dug deeper by studying 62 olfactory receptors, which play a key role in the sense of smell, finding that four were activated by tears, but not saline.

They also hooked study participants to MRI machines and noted that after smelling tears, the areas of the brain linked to aggression — the prefrontal cortex and the anterior insula — were less active.

Scientists believe that the substance of tears may have evolved to protect babies from harm.

“Babies can’t say: ‘Stop being aggressive towards me.’ They are very limited in their ability to communicate, and they are helpless as well. They have a vested interest in lowering aggression and that reflects the sad reality of aggression towards babies,” Noam Sobel, a Weizmann professor of neurobiology, told the Guardian. 

Dr. Minna Lyons, a Liverpool John Moores University psychologist, told the Guardian that the findings are “remarkable,” but people shouldn’t draw significant conclusions. 

“In real life, things may play out differently. The tears of the target of domestic violence may do little in reducing aggression of the perpetrator. Why does the chemosignaling not work in these circumstances?” she said. 

“The social context of crying is massively complicated, and I suspect the reduction of aggression is just one of the many potential functions of tears,” Lyons added.